One of the existing methods that continuously carries out after-treatments of coarse aluminum castings that have been taken out of a casting machine is one in which a first and a second machining unit are placed side by side, and one robot carries one by one the coarse aluminum castings to the first and the second machining unit and takes them out one by one.
However, according to the existing method of after-treatment for coarse aluminum castings as constructed above, the robot cannot efficiently hold and carry them to the first and the second machining unit.